1. Field of the Invention
The invention concerns an exhaust gas chimney with an inner shell in the form of a metal tube, especially an exhaust gas chimney installed directly downstream of a gas turbine or downstream of a waste heat recovery boiler of a gas turbine, wherein the inner tube is surrounded by a sound absorption ring which is joined to the inner shell and filled with bulk material.
2. Description of the Related Art
Furnaces in the broad sense carry their combustion gases into the atmosphere through an exhaust gas chimney. Mainly thin-walled metal tubes are used as inner shells of chimneys in the industrial sector. To reduce the sound emissions that are produced by the upstream combustion process, external insulation for the exhaust gas chimneys is often used, and sound absorption elements are often used on the inside of the exhaust gas chimneys or their feed lines.
With increased demands for noise reduction, the mufflers installed in the gas stream are no longer adequate, and additional damping of the chimney body is required. To this end, the inner shell of the chimney is surrounded with a sound absorption ring filled with bulk material to achieve sound decoupling and sound damping of the chimney body. Bulk material damping rings of this type were previously welded directly on the chimney as closed rings with a rectangular cross section.
The inner shell of the chimney is heated relatively quickly by the exhaust gases. If reinforcing or sound-absorbing material accumulations on the chimney structure are necessary, delayed heating occurs, which can lead to very high thermal stresses, depending on the rate of temperature increase. For example, exhaust gas chimneys for gas turbine installations can be influenced to only a very limited extent with respect to temperature control and, in addition, have a high temperature level. In this regard, there have been incidents of damage to chimney systems due to excessively high thermal stress.